General Dynamics F-111
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The General Dynamics F-111 Aardvark (the nickname was unofficial for most of its lifespan, but it was officially named "Aardvark" at its retirement ceremony for the United States Air Force) is a long-range strategic bomber, reconnaissance, and tactical strike aircraft. The F-111 project was long considered an expensive failure, but the end result was a capable, albeit costly, aircraft.
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Development
The F-111's beginnings were in the TFX, an ambitious early 1960s project to combine the U.S. Air Force requirement for a fighter-bomber with the U.S. Navy's need for a long-range carrier defense fighter to replace the F-4 Phantom II and the F-8 Crusader. The fighter design philosophy of the day concentrated on very high speed, raw power, and air-to-air missiles.
The USAF's Tactical Air Command (TAC) was largely concerned with the fighter-bomber and deep strike/interdiction role, which in the early 1960s still focused on the use of nuclear weapons. In June 1960 the USAF issued a specification for a long-range interdiction/strike aircraft able to penetrate Soviet air defenses at very low altitudes and very high speeds to deliver tactical nuclear weapons against crucial Soviet targets like airfields and supply depots. Included in the specification were a low-level speed of Mach 1.2, a high-altitude speed of Mach 2.5, a combat radius of 890 mi (1,475 km), good short-field performance, and a ferry range long enough to reach Europe unrefueled. Dogfighting maneuverability and cannon armament were considered of little importance. This would change within a few years as experience showed that close-in dogfighting remained important in air combat: guns and an emphasis on agility were reintroduced to fighter design, but only after the F-111 was developed.
The U.S. Navy, meanwhile, had since 1957 been searching for a long-range, high-endurance interceptor to defend its carrier groups against the new generation of Soviet jet bombers, which by then were being armed with huge anti-ship missiles with nuclear warheads. The Navy needed a Fleet Air Defense (FAD) aircraft with better loitering performance and load-carrying ability than the F-4 Phantom II, equipped with a powerful radar and a battery of long-range missiles to intercept both bombers and their missiles.
Since the cancellation of the F6D Missileer in December 1960 the Navy had been reconsidering variable geometry for the FAD requirement. The trend toward ever bigger, more powerful fighters posed a problem for the Navy: the current generation of naval fighters were already barely capable of landing on an aircraft carrier deck, and a still larger and faster fighter would be pose even greater problems. An airframe optimised for high speed — most obviously with a high-angle swept wing — is inefficient at cruising speeds, which reduces range, payload, and endurance, and leads to very high landing speeds. On the other hand, an airframe with a straight or modestly swept wing, while easier to handle and able to carry heavy loads over longer distances on a minimum of fuel, has lower ultimate performance. Variable geometry, which the Navy had tried and abandoned for the XF10F Jaguar in 1953, offered the possibility of combining both in a single airframe.
Both of these requirements were about to be marred by politics, and then checkered by considerable controversy. Newly appointed Secretary of Defense Robert McNamara, who had just come from a successful stint as president of the Ford Motor Company, was a great believer in "commonality" — adapting a single common mechanical platform that could be customized for various applications. He felt that imposing this principle on military procurement would lead to substantial cost savings. As a result, on 16 February 1961, less than a month after taking office, McNamara ordered the services to consider a single basic aircraft that could be developed in different versions for each service. At one stage, it was even planned to use it for the U.S. Army and Marine Corps as a close air support platform. Although the services insisted that a single aircraft was not technically feasible, McNamara ordered the development of a common aircraft to proceed anyway.
The program was dubbed TFX (Tactical Fighter Experimental). Requests for proposals were issued to Boeing, General Dynamics, Lockheed, Northrop, Grumman, McDonnell, Douglas Aircraft, North American Aviation, and Republic Aviation. Nine proposals were received in December 1961, and while the USAF and Navy felt that none were entirely suitable, on 19 January 1962 they indicated that the Boeing and General Dynamics proposals looked most promising.
After a series of subsequent proposals, in September 1962 the USAF and Navy indicated the preferred the Boeing design, but McNamara again overrode their decision, and the Department of Defense awarded the contract to General Dynamics on 24 November 1962, in part because the General Dynamics design promised to be more affordable and allow greater commonality — a decision that was to seem particularly ironic consider what followed. Grumman, which had greater experience with carrier aircraft, was engaged as the primary subcontractor.
The TFX design eventually emerged as an aircraft in the 20-ton (empty) class with a maximum take-off weight of almost 50 tons. It had been intended to use titanium for large portions of the airframe to save weight, but this proved prohibitively expensive. The TFX was powered by two afterburning Pratt & Whitney TF30-P-100 turbofans in the 80 kN class. The shoulder-mounted wings were attached to a pair of giant pivots, allowing it to take off, land, and loiter with a modest 16° sweep (for maximum lift and minimum landing speed), cruise at high subsonic speeds with a 35° sweep, or sweep back to a 72.5° maximum for fast supersonic dashes at more than Mach 2. Despite its high maximum speed, its modest thrust fraction (thrust-to-weight ratio) made early versions somewhat underpowered, exacerbated by compressor stalls and other engine problems that forced a hasty redesign of the engine inlets.
Largely at Navy insistence, the F-111 had a crew of two seated side-by-side, and production versions did not have ejection seats, instead using a pressurized crew compartment that could be ejected as a self-contained escape capsule. If deployed, it blew the nose off the aircraft and descended under a 70 ft (21 m) parachute. The escape module meant that two crew could work in "shirt sleeves" without pressure suits or oxygen masks.
First flight of the F-111A, as the USAF version was designated, was 21 December 1964, and entry into service with the USAF began 18 July 1967.
The Navy version, the F-111B, was cancelled in December 1968 to be replaced by the F-14 Tomcat, but other F-111 variants went on to serve with the USAF through the mid-1990s, performing with distinction in the 1991 Gulf War. Although the United Kingdom had expressed interest in the program in 1967, the British F-111 was cancelled, and the F-111's only export customer was the Royal Australian Air Force.
The F-111 was the first regular production variable-geometry aircraft because the earlier Navy XF10F Jaguar had been cancelled in 1953, and the first supersonic swing-wing aircraft. Despite its clear advantages, variable geometry remains a relatively unusual feature in military aircraft, due to higher cost, and the extra weight imposed by the swing wing mechanism. Nevertheless, several other types have followed, including the Soviet Sukhoi Su-17 'Fitter' (1966), Mikoyan-Gurevich MiG-23 'Flogger' (1967) and Tupolev Tu-160 'Blackjack' bomber (1981), the U.S. F-14 Tomcat naval fighter (1970) and B-1B Lancer bomber (1974), the European Panavia Tornado (1974). Of notable interest is the Sukhoi Su-24 'Fencer' (1970), which bears a more than superficial resemblance to the F-111, albeit possessing less capability.
Armament
Although conceived as a multi-role fighter, the F-111 became a long-range attack aircraft primarily armed with air-to-surface ordnance.
Weapons Bay
The F-111 has a small internal weapons bay under the fuselage for various weapons.
- Cannon: All tactical combat versions (i.e., not the EF-111A or FB-111A/F-111G) could carry a single M61 Vulcan 20mm cannon with a very large (2,084 round) ammunition tank, covered by an eyelid shutter when not in use. Although carried by some USAF aircraft, the cannon was never actually used in combat, and was removed by the early 1980s; provision for the cannon has also been deleted from Australian F-111Cs.
- Bombs: The bay can alternately hold two conventional bombs, usually the Mk 117 type of nominal 750 lb/340 kg weight, although weapons up to the Mk 118 (3,000 lb/1,362 kg) were cleared.
- Nuclear weapons: All F-111 models except the EF-111A and the Australian F-111C were equipped to carry various free-fall nuclear weapons: tactical models generally carried the B43, B57, or B61, the FB-111A those weapons or the B83. The FB-111A could also carry one or two AGM-69 SRAM nuclear missiles in its weapons bay.
- Sensor pod: The F-111C and F-111F were equipped to carry the AN/AVQ-26 Pave Tack targeting system on a rotating carriage that kept the pod protected within the weapons bay when not in use. Pave Tack is a FLIR and laser rangefinder/designator that allows the F-111 to designate and drop laser-guided bombs.
- Reconnaissance pallet: Australian RF-111Cs carry a package of reconnaissance sensors and cameras for tactical recce missions. It contains two video cameras, a Honeywell AN/AAD-5 infrared linescan (recorded on video or film), a Fairchild KA-56E low-altitude and KA-93A4 high-altitude panoramic cameras, and a pair of CAI KS-87C split vertical cameras. It can also record photographs of the attack radar's display.
- Missiles: The F-111B was intended to be capable of carrying two AIM-54 Phoenix air-to-air missiles in the bay. General Dynamics proposed an arrangement that would allow two AIM-9 Sidewinders to be carried on a trapeze mounting in the bay (at the expense of the M61 cannon), along with a single (usually nuclear) bomb. This was not adopted, with the USAF and RAAF opting for the cannon instead.
- Other equipment: Auxiliary fuel tanks and baggage pods were sometimes carried.
External Ordnance
The design of the F-111's fuselage prevents the carriage of external weapons under the fuselage (although there are two small stations, one on the weapon bay, the other on the rear fuselage between the engines, for ECM pods). All aircraft have provision for eight underwing pylons, four under each wing, with a capacity of 6,000 lb (2,722 kg) each. The inner pylons (3, 4, 5, and 6) pivot with the wing. The outer pylons (1, 2, 7, and 8) are fixed, and can be loaded only if the wings are spread at less than 26°. The outermost pylons (1 and 8) have never been used operationally, and the second pair of fixed pylons (2 and 7) are fitted only rarely for the carriage of fuel tanks. FB-111/F-111G models have provision to jettison their empty pylons in flight, reducing drag.
The primary external armament of USAF tactical F-111s included:
- Free-fall GP bombs:
- Cluster bombs
- BLU-109 (2,000 lb/907 kg) hardened penetration bomb
- Paveway laser-guided bombs, including:
- BLU-107 Durandal runway-cratering bomb
- GBU-15 electro-optical bomb (using a Mk 84 or BLU-109 penetration weapon with a TV or infrared TV seeker from an AGM-65 Maverick, with guidance via an AXQ14 or ZWS-1 datalink pod
- AGM-130 stand-off bomb (essentially a Mk 84 or BLU-109 with GBU-15 guidance and a rocket booster, making it a powered missile with a range of 40 miles (64 km)).
Although all F-111s can carry laser-guided munitions, only those with Pave Tack (i.e., F-111F and Australian F-111C) are capable of designating targets. Others can drop laser-guided weapons only with the aid of another ground or air designator.
From the early 1980s onward, tactical F-111s were fitted with shoulder rails on the sides of the outboard swiveling pylon (designated stations 3A and 6A) for two AIM-9 Sidewinder air-to-air missiles for self-defense. The standard Sidewinder fit was the AIM-9P, rather than the more modern AIM-9L or AIM-9M, whose larger fins were not compatible with the shoulder rail. The RAAF has considered replacing the Sidewinder with ASRAAM.
FB-111As could carry the same conventional ordnance as their tactical brothers, but their wing pylons were more commonly used for either fuel tanks or strategic nuclear gravity bombs. Until the weapon was withdrawn in 1990, they could carry up to four AGM-69 SRAM nuclear missiles on the wing pylons, although two was the more normal fit.
Australian F-111Cs are not nuclear-capable, but have been equipped to launch the AGM-84 Harpoon anti-ship missile, AGM-88 HARM anti-radiation missile, and the AGM-142 Popeye stand-off missile.
Service life
The F-111 was in service with the USAF from 1967 through 1998. It entered active service with the Royal Australian Air Force in 1973 and is currently scheduled to remain with the RAAF until 2010. There are concerns by some that this will leave a capability gap in the event of a delay in F-35 Joint Strike Fighter deliveries.
Variants
F-111A
The F-111A was the initial production version of the F-111. It had TF30-P-3 engines with 12,000 lbf (53.38 kN) dry and 18,500 lbf (82.29 kN) afterburning thrust and "Triple Plow I" variable intakes, providing a maximum speed of Mach 2.2 (1,453 mph / 2,325 km/h) at altitude.
The -A's Mark I avionics suite included the General Electric AN/APQ-113 attack radar mated to a separate Texas Instruments AN/APQ-110 terrain-following radar under the nose and a Litton AJQ-20 inertial navigation and nav/attack system.
Total production of the F-111A was 158, including 17 preproduction aircraft that were later brought up to production standards.
The first production F-111s were delivered on 18 July, 1967 to the 428th, 492nd and 430th Tactical Fighter Squadrons of the 474th Tactical Fighter Wing based at first out of Cannon AFB, New Mexico, which relocated in 1968 to Nellis AFB.
After early testing a detachment of six aircraft were sent in March 1968 to Southeast Asia for Combat Lancer testing in real combat conditions in Vietnam. In little over a month, three aircraft were lost and the combat tests were halted. It turned out that all three had been lost through malfunction (primarily with the terrain-following radar), not by enemy action. This caused a storm of political recrimination, with U.S. Senators denouncing Secretary of Defense McNamara's judgment in procuring the aircraft.
Behind the scenes, lessons were being learned and fixes being applied, but it was not until July of 1971 that the 474th TFW was fully operational. Testing in 1969 had revealed that a contractor had been paying off inspectors to approve sub-standard work on structural wing components, and all aircraft had to have the component replaced at significant cost (since most F-111As had been already completed). More failures were found and corrected in the wing pivot forgings.
1972 saw the F-111 back in Vietnam, participating in the Linebacker II aerial offensive against the North. F-111 missions did not require tankers nor ECM support, and they could operate in weather that grounded most other aircraft. One F-111, could carry the bomb load of four F-4 Phantom IIs. The worth of the new planes was beginning to show, and over 4,000 combat F-111A missions were flown over Vietnam with only six combat losses.
In 1977 the remaining F-111As were transferred to the 366th TFW based at Mountain Home AFB, equipping the 389th and 391st TFS.
In 1982 four surviving F-111As were converted to F-111C standard and provided to Australia as attrition replacements. They were fitted with the longer-span wings and reinforced landing gear of the -C, and subsequently were almost indistinguishable from new-build F-111Cs. Some of the -As delivered to the RAAF were Vietnam veterans, purportedly still bearing the scars of anti-aircraft fire.
42 F-111As were converted to EF-111A Raven standard for electronic warfare roles.
Three pre-production -As were provided to NASA for various testing duties. One was fitted with a variable-camber wing as part of the Advanced Fighter Technology Integration program in the 1980s; it was retired to the United States Air Force Museum at Wright Patterson AFB in 1989.
Most of the unconverted surviving F-111As were retired in 1992 and mothballed at AMARC, Davis Monthan AFB.
F-111B
The F-111B was to be a fleet-defense fighter for the U.S. Navy, fulfilling a long-standing naval requirement for a fighter capable of carrying heavy, long-range missiles to defend carriers from Soviet anti-ship missiles. The F-111B was equipped with the Hughes AN/AWG-9 pulse-Doppler radar and up to six of the new AIM-54 Phoenix long-range air-to-air missiles. General Dynamics, having no experience with carrier-based aviation, partnered with Grumman for this version.
The F-111B was a compromise that attempted to reconcile the Navy's very different needs with an aircraft whose configuration was largely set by the USAF need for a supersonic strike aircraft, and those compromises were to prove its undoing. The B was shorter than the F-111A, to enable it to fit on carrier lifts, but had a longer wingspan (70 ft/21.3 m compared to 63 ft/19.2 m) for increased range and cruising endurance. Although the Navy had wanted a 48 in (122 mm) radar dish for long range, they were forced to accept a 36 in (91.4 mm) dish for compatibility. The Navy had requested a maximum take-off weight of 50,000 lb (22,686 kg), but Secretary of Defense McNamara forced them to compromise at 55,000 lb (24,955 kg). This proved to be overly optimistic.
Weight plagued the B throughout its development. Not only were prototypes far over the 55,000 lb limit, efforts to redesign the airframe only made matters worse. The excessive weight made the aircraft seriously underpowered. Worse, its visibility for carrier approach and landing were abysmal, and its maneuverability—especially in the crucial medium-altitude regimen—was decidedly inferior to the F-4 Phantom II.
By October 1967, the Navy was finally convinced that the F-111B program was a lost cause and recommended its cancellation, which occurred in 1968. The Phoenix missiles and radar developed for this plane (and the earlier, cancelled F6D Missileer) were eventually used on its replacement, the F-14 Tomcat.
F-111C
The F-111C was an export version for Australia, combining F-111A/E avionics with the long-span wings and heavier landing gear of the F-111B. Twenty-four were originally ordered in 1963, although development delays and structural problems kept them from entering service until 1973.
Four aircraft were modified to RF-111C reconnaissance configuration, retaining their strike capability.
The only F-111 model still in service, F-111C aircraft have been equipped to carry Pave Tack FLIR/laser pods, and later underwent an extensive Avionics Upgrade Program, with AN/APQ-169 attack radar replacing the elderly AN/APQ-113, Texas Instruments AN/APQ-171 terrain-following radar, twin Honeywell H423 ring-laser gyro INS, GPS receiver, modern digital databus, mission computer, and stores-management system, and cockpit multi-function displays (MFDs). Their engines were updated to TF30-P-108/109RA standard, with 21,000 lbf (93.4 kN) thrust. Four ex-USAF F-111As were refitted to F-111C standard and delivered to Australia as attrition replacements.
A series of upgrades has kept the Australian F-111 fleet up to date, and it is planned to keep them in service until about 2010.
F-111D
The F-111D was an upgraded F-111A equipped with newer Mark II avionics, more powerful engines, improved intake geometry, and an early "glass cockpit." First ordered in 1967, extensive development problems delayed service entry until 1974, and only 96 were built.
The F-111D used the new Triple Plow 2 intakes, which were located four inches (about 10 cm) further away from the airframe to prevent engine ingestion of the sluggish boundary layer air that was known to cause stalls in the TF30 turbofans. It had more powerful TF30-P-3 engines with 12,000 lbf (53.4 kN) dry and 18,500 lbf (82.3 kN) afterburning thrust.
More significant--and problematic--were the Mark II avionics. These were digitally integrated microprocessor systems, some of the first used by the USAF, offering tremendous capability, but substantial teething trouble. The main radar was the General Electric AN/APQ-114, with Doppler beam-sharpening, moving-target indicator (MTI), and continuous-wave mode for guiding semi-active radar homing missiles (which the standard AN/APQ-113 set could not). This was matched with an Autonetics inertial navigation/attack radar system, Marconi Doppler radar for navigation, a horizontal situation display, an IBM processor, and a Norden integrated systems display, with modern multi-function displays (MFDs). These last proved to be a major source of trouble, serving to multiply the development problems experienced with the individual systems. Considerable acrimony between the contractors resulted, and it took years before the bugs were worked out. F-111 crews considered the -D the most capable (and user-friendly) version of the aircraft when everything worked, but that was all too rare before the 1980s.
Incidentally, the F-111D was never equipped to carry what proved to be the 'Aardvark's' most useful sensor system, the AN/AVQ-26 Pave Tack pod.
The F-111D was withdrawn from service in 1992 for mothballing at AMARC.
F-111E
The F-111E was a simplified, interim model ordered after the prolonged teething troubles of the F-111D. It used the -D's Triple Plow 2 intakes and more powerful TF30-P-3 engines, but retained the -A's Mark I avionics.
Although conceived after the -D, the F-111E was actually delivered before it. The first flight of an -E was 20 August 1969. A total of 94 were built.
Some F-111Es were based at RAF Upper Heyford in Oxfordshire (United Kingdom) until 1993, and the type saw service in Operation Desert Storm. All F-111Es were withdrawn to storage in 1993 and 1994.
F-111F
The F-111F was the final F-111 variant produced for Tactical Air Command, with more modern and advanced Mark IIB avionics that were more capable than the F-111E and much more reliable than the F-111D. A total of 106 were produced between 1971 and 1976. The aircraft were mostly assigned to the 48th TFW based at RAF Lakenheath in the United Kingdom, with some assigned to the 57th Fighter Weapons Wing at Nellis AFB.
The F-111F's Mark IIB avionics suite used a simplified version of the FB-111A's radar, the AN/APQ-144, lacking some of the strategic bomber's operating modes but adding a new 2.5 mi (4.0 km) display ring. Although it was tested with digital moving-target indicator (MTI) capacity, it was not used in production sets. It used Texas Instruments AN/APQ-146 terrain-following radar, Litton inertial navigation, and the F-111E's Weapon Control Panel. The internal weapons bay was normally occupied by a AVQ-26 Pave Tack FLIR and laser designator system for the delivery of precision laser-guided munitions. The radar was subsequently upgraded to AN/APQ-161, with the AN/APQ-171 terrain-following set. The later Pacer Strike avionics update program added new digital electronics and databus.
The -F also used the Triple Plow 2 intakes, along with the substantially more powerful TF30-100 turbofan with 25,100 lbf (111.6 kN) afterburning thrust. This substantially improves the -F's performance, allowing a top speed of Mach 2.5 at altitude and enabling an unloaded F-111F to supercruise (fly at supersonic speeds without afterburner).
The F-111F made its combat debut in Operation El Dorado Canyon against Libya in 1986, and performed superbly in Operation Desert Storm against Iraq, where it unexpectedly added the anti-armor ("tank-plinking") role to its resume.
Various plans to upgrade the F-111F, including the adoption of the General Electric F110 engine (used in the F-14D Tomcat), were proposed, but not implemented because they might have interfered with the USAF's political efforts to build the F-22 Raptor. As a result, the last USAF F-111s were withdrawn from service on 27 July 1996, replaced by the F-15E Strike Eagle.
FB-111A strategic bomber
The FB-111A was a strategic bomber version of the F-111 developed as an interim aircraft for the Strategic Air Command to replace the B-58 Hustler and early models of the B-52 Stratofortress. The planned replacement program, the Advanced Manned Strategic Aircraft, was proceeding slowly, and the Air Force was concerned that fatigue failures in the B-52 fleet would leave the strategic bomber fleet dangerously under strength. Although 263 planes were planned originally, the total was finally cut to just 76. The first production aircraft was delivered in 1968. The FB-111A never had an official popular name, but it was commonly called the "Switchblade."
The FB-111A was 2 ft 1.5 in (650 mm) longer than the F-111A, allowing carriage of about 585 gallons (2,214 L) extra fuel, and was fitted with the longer wings of the abortive F-111B and F-111K for greater range and load-carrying ability. A stronger undercarriage and landing gear compensated for the higher take-off weights (gross weight rose to 119,250 lb/54,105 kg). All but the first aircraft had the Triple Plow 2 intakes and the TF30-P-7 with 12,500 lbf (55.58 kN) dry and 20,350 lbf (90.49 kN) afterburning thrust.
The FB-111A had new electronics, known as the SAC Mk IIB suite. The Mk IIB retained the F-111A's Texas Instruments AN/ANPQ-134 terrain-following radar and Honeywell AN/APN-167 radar altimeter. Radar was the General Electric AN/APQ-114, with a new north-oriented display, a beacon tracking mode, and a photo recording mode. To those components, the FB-111A added a Rockwell AN/AJN-16 inertial navigation system, Singer-Kearfott AN/APN-185 Doppler radar, and the Litton AN/ASQ-119 Astrotracker astrocompass, which allowed navigation by stellar positioning (a similar system had been used on the SR-71 Blackbird). A Horizontal Situation Display was added along with the AN/AYK-6 cockpit display. A unique feature of the FB-111A was that the TFR was integrated into the automatic flight control system, allowing "hands-off" flight at high speeds and low levels (down to 200 feet), even in adverse weather.
Armament for the strategic bombing role was the Boeing AGM-69 SRAM (short-range attack missile), two of which could be carried in the internal weapons bay and two more on the inner underwing pylons. Nuclear gravity bombs were also typical FB armament, although it could also carry a substantial conventional bombload to a theoretical total of fifty 750 lb (340 kg) M117 weapons. In 1990, the SRAM was withdrawn from service amid concerns about the integrity of its nuclear warhead in the case of fire, and subsequently only unpowered bombs were available.
The FB-111 became surplus to SAC's needs after the introduction of the Rockwell B-1B Lancer, and the remaining FB-111s were converted to a tactical configuration and renamed the F-111G. They were used primarily for training.
The F-111G did undergo an avionics upgrade program that added a digital computer, dual AN/ASN-41 ring-laser gyro INS, AN/APN-218 Doppler navigation, and an updated terrain-following radar. The astrocompass system was deleted.
The G model did not remain in USAF service for long, being mothballed in 1993, but 15 were bought by Australia to supplement its F-111Cs.
Several "stretched" FB-111 variants (the FB-111B, with F101 engines and a longer fuselage, and the greatly enlarged FB-111H, intended as a competitor for the B-1 Lancer) were proposed in the late 1970s, but none were ever built.
EF-111A Raven electronic warfare aircraft
To replace the elderly and obsolescent Douglas EB-66, in 1972 the USAF contracted Grumman to convert some existing F-111As into electronic warfare/ECM aircraft. The Air Force had considered the Navy Grumman EA-6B Prowler, but was reluctant to adopt a Navy aircraft.
A contract to develop the EF-111A was awarded to Grumman in 1974, modifying existing -A airframes. The first fully equipped model flew on 10 March 1977, and deliveries to combat units began in 1981. A total of 42 conversions was completed, the last delivered by the end of 1985. The EF-111A received the official popular name Raven, although in service it acquired the nickname "Spark 'Vark".
The Raven retained the F-111A's navigation systems, with a revised AN/APQ-160 radar primarily for ground mapping. The primary feature of the Raven, however, was the AN/ALQ-99E jamming system, developed from the Navy's ALQ-99 on the Prowler. Its primary electronics were installed in the weapons bay, with transmitters fitted in a 16 ft (5 m) long ventral "canoe" radome; the complete installation weighed some 6,000 lb (2,723 kg). Receivers were installed in a fin-tip pod,or "football," similar to that of the EA-6B. The aircraft's electrical and cooling systems had to be extensively upgraded to support this equipment. The cockpit was also rearranged, with all flight and navigation displays relocated to the pilot's side, and flight controls except throttles being removed from the other seat, where the electronic warfare officer's instrumentation and controls were installed.
EF-111s were unarmed, although a few sources indicated that the inner wing pylons could be fitted to allow carriage of AIM-9 Sidewinders for self-defense. The aircraft's considerable speed and acceleration were its main means of self-defense. The EF-111 was not capable of firing AGM-45 Shrike, AGM-78 Standard, or AGM-88 HARM missiles in the lethal SEAD role, which was a tactical limitation.
In 1986 the EF-111A's engines were upgraded to the more powerful TF30-P-9 of the -D model, with 12,000 lbf (53.4 kN) dry and 18,500 lbf (82.3 kN) afterburning thrust.
From 1987 to 1994 the Spark 'Vark underwent an Avionics Modernization Program (AMP), similar to the Pacer Strike program for the F model. This added a dual AN/ASN-41 ring-laser gyro INS, AN/APN-218 Doppler radar, and an updated AN/APQ-146 terrain-following radar. Cockpit displays were upgraded with multi-function displays borrowed from the F-16 Fighting Falcon.
EF-111s saw combat use during Operation Eldorado Canyon (the 1986 retaliatory attack on Libya) and Operation Desert Storm in 1991. On 17 January 1991, a USAF EF-111 was credited with a kill against an Iraqi Dassault-Breguet Mirage F1, which it managed to maneuver into the ground, making it the first and only F-111 to achieve an aerial victory over another aircraft.
The last deployment of the Raven was a detachment of EF-111s stationed at Al Kharj Air Base in Saudi Arabia until April 1998.
Shortly afterward, in May 1998, the USAF withdrew the final EF-111As from service, placing them in storage at AMARC. These were the final F-111s in service with the USAF. In the short term, EA-6B Prowlers are fulfilling this function for both the Navy and Air Force, but the EA-18G Growler, which is now in production, is expected to perform this role in the long term.
Foreign sales
Australia
The Australian government ordered 24 F-111 aircraft in 1963 to replace the RAAF's English Electric Canberra in the bombing and tactical strike role. While the first aircraft was officially handed over in 1968, structural integrity problems found in the USAF fleet delayed the service entry of the F-111C until 1973, USAF F-4 Phantom IIs being leased as an interim measure. Four aircraft were modified to RF-111C reconnaissance configuration, retaining their strike capability.
A number of ex-USAF aircraft have been delivered to Australia, as attrition replacements and to enlarge the fleet. Four aircraft modified to F-111C status were delivered in 1982, while eighteen F-111G aircraft were purchased in 1992 and delivered in 1994. Additional stored USAF airframes are reserved as a spares source.
Australian F-111s equip No. 1 Squadron and No. 6 Squadron of the RAAF, and are likely to remain in service through 2010.
In Australian military and aviation circles, the F-111 Aardvark is affectionately known as the 'Pig,' because of it's ability to hunt amongst the weeds like its namesake, referring to the F-111's unique Terrain Following ability.
An RAAF F-111C with wings swept fully back doing a "torching" (dump and burn) routine.
United Kingdom
Upon cancellation of the BAC TSR-2, the British government ordered 50 F-111K aircraft in 1967. However, the order was cancelled just over a year later; the reason given was the escalating F-111 price.
Specifications
General characteristics
- Crew: Two (pilot and weapons system operator)
- Length: 22.4 m (73.5 ft)
- Wingspan: 19.2 m (63.0 ft) spread; 9.74 m (32.0 ft) swept
- Height: 5.22 m (17.13 ft)
- Wing area: 61.07 m² (657.4 ft²) spread; 48.77 m² (525 ft²) swept
- Empty: 21,537 kg (47,481 lb)
- Loaded: 37,577 kg (82,843 lb)
- Maximum takeoff: 44,896 kg (98,979 lb)
- Unit cost: $15 million.
- Powerplant: 2 × Pratt & Whitney TF30-P-100 turbofans with afterburner, each 25,100lbf (111.7 kN)
Performance
- Maximum speed: Mach 2.5 (2,660 km/h or 1,653 mph) (high altitude)
- Combat radius: 2,128 km (1,330 mi)
- Ferry range: 5,184 km (3,634 mi)
- Service ceiling: 17,270 m (56,650 ft)
- Rate of climb: 7,890 m/min (25,550 ft/min)
- Wing loading:
- Thrust-to-weight ratio:
Armament
- 1 × M61 Vulcan 20mm rotary cannon (seldom fitted)
- 14,288 kg (31,500 lb) warload
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